a. Field of the Invention
The instant invention relates to catheters that are used in the human body. In particular, the instant invention relates to catheters using multiple polymeric and reinforcing layers to improve kink resistance, pushability, and torqueability.
b. Background Art
Catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, the catheter is manipulated through the patient's vasculature and to the intended site, for example, a site within the patient's heart. The catheter typically carries one or more electrodes, which may be used for ablation, diagnosis, or the like.
Since the path through the patient's vasculature to the intended site is often long and tortuous, steering forces typically must be transmitted over relatively great distances. Accordingly, it is desirable for a catheter to have sufficient axial (e.g., column) strength to be pushed through the patient's vasculature via a force applied at its proximal end (“pushability”). It is also desirable for a catheter to transmit a torque applied at the proximal end to the distal end (“torqueability”). Pushability and torqueability (collectively, “maneuverability”) permit a physician to manipulate a catheter to an intended site and then properly orient the catheter. It is also desirable for a catheter to have sufficient flexibility to substantially conform to the patient's vasculature and yet resist kinking as it does so. Kinking is often the result of a localized failure of the material of the catheter when localized stresses exceed the yield strength of the material.
To provide pushability, torqueability, flexibility, and kink resistance, many extant catheters are made of engineering polymer materials reinforced with metallic wire reinforcing layers. The characteristics of pushability, torqueability, flexibility, and kink resistance are often in tension with one another, however, with improvements in one requiring compromises in others.